1. Field of the Invention
This invention relates to a catalyzer apparatus for purifying emission gas of an automobile engine.
2. Description of the Related Art
A known catalyzer control apparatus, as disclosed in SAE, Technical Paper, Series 900503 (1990), pages 61 to 70 for purifying exhaust gas from an internal combustion engine has a converter with a resistor-type metal substrate which is heated to improve cold start emission characteristics. Such electrically heated monoliths have been designed to reach catalytic working temperatures of about 350.degree. C. in less than thirty seconds using the conventional 12 V electrical system. Thus, means are provided for applying a heating current to the catalyzer and temperature detection means are provided for detecting the temperature of the catalyzer so as to control the heat applying means so that the temperature of the catalyzer is raised toward a desired working temperature.
Because the amount of energy required to heat the catalyzer is approximately 4.7 Kw, a considerable strain is placed upon the conventional battery, resulting in battery drain. Because it is desired to heat the catalyzer prior to starting the engine so that it is closer to its working temperature at the time of engine start to thereby minimize pollution, so the drain on the battery in heating the catalyzer often results in the battery charging capacity dropping so that the engine cannot be started by its normally provided starter motor.
This invention seeks to overcome the foregoing difficulty.
A primary object of this invention is to ensure the startup of an engine by isolating the power supply for supplying current to the catalyzer from that for starting the engine.
A second object of this invention is to raise power transmission efficiency by providing the said isolated power supply with a higher voltage than that of the power supply for starting the engine, thereby providing an inexpensive, lightweight control apparatus.